ansible如何为变量赋值？

- hosts: all
  vars:
    my_var: "Hello, Ansible!"
  tasks:
    - name: Print variable
      debug:
        var: my_var

my_var: "Hello, Ansible!"

- hosts: all
  vars_files:
    - vars.yml
  tasks:
    - name: Print variable
      debug:
        var: my_var

ansible-playbook playbook.yml -e "my_var=Hello, Ansible!"

- name: Execute command and register variable
  command: echo "Hello, Ansible!"
  register: result

- name: Print variable
  debug:
    var: result.stdout